An E10 yes, but it's not a perfect pairing. It won't be so overwhelming that you'll regret buying the 6xx. But the E10s spec sheet says 150 ohms is "suitable" the 6xx is double that. The 6xxs may sound quiet or not like how they're supposed to, depending on how far you're comfortable pushing the E10. Maybe look into a cheap, more powerful amp after getting them. A magni 2, (my personal amp) has no problem powering up to 600 ohms at loud volume. And it's only a 20-30 dollar jump over the E10. I believe you could still daisy chain the E10 DAC to another amp and just get more power but the choice is yours on that. To answer your question an E10 will push the 6xx but not as loudly as you may prefer.

In addition to previous statement, it will also lack presentation/sound-stage and will not have enough amp grunt to open these cans up. Also, and this is my opinion, the Magni 2 is a great amp but sounds bright with these cans. I use an SMSL VMV VA2 that I picked up on Amazon for $105 (for the black edition - the silver edition runs about 25% more for some reason) and it is warmer with my Senn HD 700's than with the Schiit. Now my Magni 2 U collects dust. That being said, the 700's and the 650's are very close to each other in sound signature from what I understand. Also, sound being very subjective, you may like brightness over warmth. That is for you to decide. I must also state that I believe the quality of the Magni 2 to be overall better than the SMSL, but I have not any issues with either amp thus far, just going from what i have read others say on HeadFi.